Kubota B5100

Kubota B5100The Kubota B5100 is a sub-compact utility tractor model manufactured from 1978 to 1984 by Kubota in Japan. It was available in two-wheel drive (B5100E) or four-wheel drive (B5100DT) versions.

The Kubota B5100 is equipped with a 508 cc (31.0 cu·in) two-cylinder diesel engine with 68.0 mm (2.68 in) of the cylinder bore and 70.0 mm (2.76 in) of the piston stroke, and a gear shift transmission with 6 forward and 2 reverse gears and dry single plate clutch.

The Kubota B5100 utility tractor features:

  • The Z500-A1 diesel engine which produces 12.0 PS (8.8 kW; 11.8 HP) at 3,000 rpm of horsepower
  • Ball screw type steering
  • Mechanical wet disc brakes
  • Open operator station with two-post ROPS
  • Category I rear hitch with 140 kg (309 lbs) of maximum lift capacity
  • Front PTO with 3,000 rpm
  • Transmission type rear PTO with 540/1,000 rpm

General specifications

General Specifications
ModelKubota B5100
Tractor typeSub-Compact utility tractor
Production years1978-1984
Dimensions and weight
Length1,820 mm (71.7 in)
Width920 mm (36.2 in)
Height (steering wheel)1,120 mm (44.1 in)
Wheelbase1,180 mm (46.5 in)
Ground clearance 2WD (rear axle): 260 mm (10.25 in)
4WD (front axle): 210 mm (8.67 in)
Front tread 2WD: 660 mm (26.0 in)
4WD: 670 mm (26.4 in)
Weight 2WD: 365 kg (805 lbs)
4WD: 405 kg (893 lbs)
Fuel capacity
Fuel tank capacity8.0 liters (2.1 US gal.; 1.8 Imp. gal)


Engine modelKubota Z500-1A
Engine type4-stroke, vertical, two-cylinders
Displacement508 cm3, (31 cu·in)
Cylinder bore:68.0 mm (2.68 in)
Piston stroke:70.0 mm (2.76 in)
Compression ratio:22.0:1
Max. horsepower9.5 PS (7.0 KW; 9.5 HP) at 3,000 rpm
Max. torque
Cooling systemLiquid-cooled
Lubricating systemForced lubrication by pump
Combustion chamberSpherical type
Fuel injection pumpBosch K-Type Mini Pump
Injection typeIndirect injection
Injection nozzleBosch throttle type
Fuel usedDiesel fuel No.2-D
Starting systemElectric starter (12V, 0.8 kW)
Starting support deviceGlow plug in combustion chamber
GovernorCentrifugal ball mechanical governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)520 x 380 x 504 mm (20.5 x 15 x 19.8 in)
Dry weight69.7 kg (153.7 lbs)
Cylinder compression pressure
Cylinder compression:31.5 kgf/cm2 (3.09 MPa, 448 psi)
Compression differential limit between cylinders:10% or less
Valve clearance
Intake valve clearance:0.150-0.200 mm (0.0059-0.0078 in)
Exhaust valve clearance:0.150-0.200 mm (0.0059-0.0078 in)
Oil system
Lubrication system:Forced lubrication by pump
Oil type:API CC or CD
Oil capacity:2.3 liters (2.43 US.qts, 2.02 Imp. qts)
Oil filter:Full flow paper filter (cartridge type)
Oil pressure: At idle spped: 68 kPa (0.7 kgf/cm2, 10 psi)
At rated speed: 196-441 kPa (2.0-4.5 kgf/cm2, 29-64 psi)
Fuel system
Injection timing:25° B.T.D.C.
Fuel injection pressure13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi)
Cooling system
Thermostat’s valve opening temperature:80.5-83.5°C (176.9-182.3°F)
Temperature at which thermostat completely opens:95°C (203°F)
Coolant capacity:3.0 liters (3.2 US.qts, 2.6 Imp. qts)

Transmission and chassis

Chassis, steering and brakes
Chassis B5100E: 4×2 2WD
B5100DT: 4×4 MFWD 4WD
Steering typeBall screw type
BrakesMechanical wet disc
Final driveInternal-expanding type, right and left independent with interlock device
Front axle differential case0.5 liters (0.53 US.qts, 0.44 Imp. qts)
Front axle gear case0.15 liters (0.16 US.qts, 0.13 Imp. qts)
Transmission manufacturer or model
Transmission typeGear shift with dry single plate type clutch
Gears6 forward and 2 reverse
Speed Forward: 12.8 kmh (8 mph)
Reverse: 6.4 kmh (4 mph)
Transmission oil capacity8.5 L (2.2 US. gal, 1.9 Imp. gal.)


Front tires Ag: 4.00-9 (2WD); 4.50-10 (4WD)
Lawn/turf: 18×6.50-8
Rear tires Ag: 7.00-16
Lawn/turf: 27×8.50-15

Rear Hitch

Three-Point Hitch
Control type
Lift capacity (at ends)140 kg (309 lbs)

PTO (Power take-off shaft)

Front PTO type
Front PTO speed3,000 rpm
Rear PTO typeTransmission
Rear PTO speed540/1,000 rpm

Electrical system

Electrical system
Charging system12V
Charging amps
Battery12V 35Ah

Hydraulic system

Hydraulic system
Hydraulic typeOpen center
Pressure1710 psi (117.9 bar)
Pump flow3.1 gpm (11.7 lpm)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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